1. X-rays from the HII Regions and Molecular Clouds near the Galactic Center
- Author
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Katsuji Koyama, Hiroshi Murakami, and Shin-ichiro Takagi
- Subjects
Physics ,Infrared ,Astrophysics::High Energy Astrophysical Phenomena ,Molecular cloud ,Young stellar object ,Galactic Center ,Astronomy ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Spectral line ,Stars ,Space and Planetary Science ,Cluster (physics) ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Galaxy Astrophysics ,Line (formation) - Abstract
We report measurements by Chandra of a variety of X-ray sources in the molecular clouds and HII regions of the Sgr B2, Arches, Quintuplet and the Galactic center clusters. Moderately bright X-ray sources are present in the Sgr B2, Quintuplet and the Galactic center clusters at the positions of ultra compact HII regions and bright infrared sources. Their X-ray spectra are fitted with models of a thin thermal plasma with 2–10 keV temperatures and luminosities of ∼1032–33erg s−1. The X-ray properties are typical of those of high-mass young stellar objects or clusters of such objects. The Arches Cluster has three bright X-ray sources, at the positions of bright IR and radio stars, with X-ray luminosities of a few ×1033 erg s−1 each, which may indicate an unusual X-ray emission mechanism from high mass YSOs. A unique X-ray feature of molecular clouds and HII regions near the Galactic center is the presence of diffuse emission with a strong 6.4 keV line; in Sgr B2 this is attributable to the fluorescence of gas irradiated by external sources in the Galactic center, while the diffuse emission from Arches is puzzling.
- Published
- 2003
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